Medical devices such as stents, stent-grafts, grafts, or vena cava filters and catheters, balloon catheters, and medical balloons for their delivery are utilized in a number of medical procedures and situations, and as such their structure and function are well known.
Catheters for example, may be used in a variety of medical procedures. An example of one potential use for a catheter is in PTCA procedures. In typical PTCA procedures, a guiding catheter is percutaneously introduced into the cardiovascular system of a patient through a vessel and advanced through therein until the distal end thereof is at a desired location in the vasculature. A guidewire and a dilatation catheter having a balloon on the distal end thereof are introduced through the guiding catheter with the guidewire sliding through the dilatation catheter. The guidewire is first advanced out of the guiding catheter into the patient's coronary vasculature and the dilatation catheter is advanced over the previously advanced guidewire until the dilatation balloon is properly positioned across the lesion. Once in position across the lesion, the flexible, expandable, preformed balloon is inflated to a predetermined size with a liquid or gas at relatively high pressures, to radially compress the arthrosclerotic plaque of the lesion against the inside of the artery wall and thereby dilate the lumen of the artery. The balloon is then deflated to a small profile so that the dilatation catheter may be withdrawn from the patient's vasculature and blood flow resumed through the dilated artery.
In angioplasty procedures of the kind described above, there may be injury to or restenosis of the artery, which either necessitates another angioplasty procedure, a surgical by-pass operation, or some method of repairing or strengthening the area. To strengthen the area and help prevent restenosis, a physician can implant an intravascular prosthesis for maintaining vascular patency, commonly called a stent, inside the artery at the lesion. The stent is expanded to a larger diameter for placement in the vasculature, often by the balloon portion of the catheter. Stents delivered to a restricted coronary artery, expanded to a larger diameter by a balloon catheter, and left in place in the artery at the site of a dilated lesion are shown in U.S. Pat. Nos. 4,740,207 and 5,007,926 among others. Several patent references such as U.S. Pat. No. 4,733,665 describe introduction of a stent over a balloon catheter.
To assist in accurate placement of the catheter and stent underneath the lesion site it is useful to visually monitor the catheter as it advances through a vessel. Fluoroscopes, X-ray machines or other similar viewing devices are used to view the catheter within the body as it is advanced. However, in order for the catheter to be visible the catheter, or a portion of the catheter, must be radiopaque. In previous catheter designs radiopaque: marker bands, stent retaining members, hubs, catheter tips, or other components have been attached to the catheter for this purpose.
An example of a catheter which utilizes an external metal radiopaque marker band is U.S. Pat. No. 5,759,174 to Fischell et al., which has a single external metal marker band which is intended to identify the central portion of a stenosis once the delivery catheter is removed. Marker bands such as those disclosed by Fischell et al. are mounted externally on the balloon of an angioplasty catheter and undesirably increase the profile of the catheter as well as its cost. Furthermore, such marker bands are constructed from expensive and heavy radiopaque metals such as gold, platinum and tantalum or alloys of these dense materials. The use of these heavy materials typically results in marker bands that are somewhat inflexible which may impair the trackability of the delivery catheter.
Despite these shortcomings, often times marker bands are preferable over radiopaque tips alone, since a radiopaque catheter tip only provides for the end of the catheter to be visible as opposed to a desired area along the catheter shaft. For example, U.S. Pat. No. 5,429,597 to Demello et al., discloses a balloon catheter having a radiopaque distal tip composed of a polymer mixed with a radiopaque powder such as tungsten.
Other references are known which provide for various radiopaque polymer complexes. For example: U.S. Pat. Nos. 4,866,132; 5,256,334; and 5,024,232, respectively disclose various methods of making radiopaque polymer complexes. In addition, the use of a compliant material to form a marker band which surrounds the external surface of a catheter body is described in U.S. Pat. No. 5,948,489.
In addition to utilizing radiopaque marker bands for observing the catheter as it is advanced through a body lumen, radiopaque materials may also be utilized in the formation of other potential catheter components such as hubs, bumpers, stops and others.
In many applications where a catheter is used to delivery a stent, graft, stent-graft, vena-cave filter, and other implantable medical devices, collectively referred to herein as stents, the inner shaft or member of the catheter, which supports the stent prior to delivery, will often employ one or more radiopaque marker bands that are positioned adjacent to one or more of the ends of the stent. The marker bands are often crimped or otherwise affixed to the inner shaft so as not to underlie the stent. Where the catheter employs a balloon for expanding or seating the stent, the stent is disposed about the body of the balloon, whereas the marker bands are positioned on the inner shaft to underlie the cones of the balloon and fall outside the balloon body and stent. The marker bands are positioned outside the length of the stent to prevent the balloon from being potentially damaged by the marker bands.
However, because the marker bands do not underlie the stent, the ability to position the stent accurately may be compromised. Furthermore, because the marker bands do not underlie the body of the balloon the precise deployment area of the balloon and thus the precise deployment area of the stent may be difficult to determine.
In light of the above, it would be desirable to provide for a catheter shaft or portion thereof that includes a radiopaque area corresponding to the length of the balloon body and/or the length of the stent to be retained thereon. The radiopaque area of the catheter shaft is constructed and arranged to allow the stent to be crimped directly thereto. Where the catheter employs a balloon, a stent may be crimped directly to the portion of the balloon that overlies the radiopaque area of the catheter shaft.
All U.S. patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.
Without limiting the scope of the invention a brief summary of some of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.
A brief abstract of the technical disclosure in the specification is provided as well only for the purposes of complying with 37 C.F.R. 1.72. The abstract is not intended to be used for interpreting the scope of the claims.